linux-kernel - Re: [RFC PATCH 0/2 shit_A shit_B] workqueue: fix wq

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Date:	Fri, 16 Jan 2015 14:22:28 +0900
From:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
To:	Lai Jiangshan <laijs@...fujitsu.com>
CC:	<linux-kernel@...r.kernel.org>, Tejun Heo <tj@...nel.org>,
	"Gu, Zheng" <guz.fnst@...fujitsu.com>,
	tangchen <tangchen@...fujitsu.com>,
	Hiroyuki KAMEZAWA <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [RFC PATCH 0/2 shit_A shit_B] workqueue: fix wq_numa bug

Hi Lai,

Thanks you for posting the patch-set.

I'll try your it next Monday. So, please wait a while.

Thanks,
Yasuaki Ishimatsu


(2015/01/14 17:54), Lai Jiangshan wrote:
> Hi, All
> 
> This patches are un-changloged, un-compiled, un-booted, un-tested,
> they are just shits, I even hope them un-sent or blocked.
> 
> The patches include two -solutions-:
> 
> Shit_A:
>    workqueue: reset pool->node and unhash the pool when the node is
>      offline
>    update wq_numa when cpu_present_mask changed
> 
>   kernel/workqueue.c | 107 +++++++++++++++++++++++++++++++++++++++++------------
>   1 file changed, 84 insertions(+), 23 deletions(-)
> 
> 
> Shit_B:
>    workqueue: reset pool->node and unhash the pool when the node is
>      offline
>    workqueue: remove wq_numa_possible_cpumask
>    workqueue: directly update attrs of pools when cpu hot[un]plug
> 
>   kernel/workqueue.c | 135 +++++++++++++++++++++++++++++++++++++++--------------
>   1 file changed, 101 insertions(+), 34 deletions(-)
> 
> 
> Both patch1 of the both solutions are: reset pool->node and unhash the pool,
> it is suggested by TJ, I found it is a good leading-step for fixing the bug.
> 
> The other patches are handling wq_numa_possible_cpumask where the solutions
> diverge.
> 
> Solution_A uses present_mask rather than possible_cpumask. It adds
> wq_numa_notify_cpu_present_set/cleared() for notifications of
> the changes of cpu_present_mask.  But the notifications are un-existed
> right now, so I fake one (wq_numa_check_present_cpumask_changes())
> to imitate them.  I hope the memory people add a real one.
> 
> Solution_B uses online_mask rather than possible_cpumask.
> this solution remove more coupling between numa_code and workqueue,
> it just depends on cpumask_of_node(node).
> 
> Patch2_of_Solution_B removes the wq_numa_possible_cpumask and add
> overhead when cpu hot[un]plug, Patch3 reduce this overhead.
> 
> Thanks,
> Lai
> 
> 
> Reported-by: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
> Cc: Tejun Heo <tj@...nel.org>
> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
> Cc: "Gu, Zheng" <guz.fnst@...fujitsu.com>
> Cc: tangchen <tangchen@...fujitsu.com>
> Cc: Hiroyuki KAMEZAWA <kamezawa.hiroyu@...fujitsu.com>
> 


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